Megacolon

Disease class: Colonic diseases

Types

• Hirschsprung disease 
• megacolon, Toxic

A megacolon is a colon with a significantly increased diameter, usually throughout a large continuous segment of bowel.

 

Investigations

• Abdominal radiograph (AXR)
• CT scan of abdomen and pelvis with bowel contrast (if possible)

 

Diagnostic tips

• Faecal loading can cause small areas of dilatation.
• It is normal for some segments of bowel to have a relatively large diameter. The "369 rule" refers to the approximate normal diameters of small bowel (up to 3cm), large bowel (up to 6cm), caecum + sigmoid colon (up to 9cm).